Traditionally, the Japanese use rapeseed meal as fertilizer. This is a non-waste production, they extract oil from seeds and use the resulting meal as fertilizer. But I wondered: is it possible to use simply crushed rapeseed seeds that have not been pressed for oil? Does the presence of oil affect the fertilizer quality, does it become dangerous for plants? Or vice versa, a large amount of oil in crushed seeds improves the fertilizer quality?

1 Answer 1


As by design whole seeds do not break down quickly in the ground, because they are built to protect the embryo, until conditions are met to germinate. Some seeds can sit dormant in the soil without changing for decades and others only a few months. It depends on the seeds. The seed shell can last in the soil unchanged even after the seed has germinated.

The food/fertiliser you are seeking for your ground will not be available until the seed begins to rot/break down. By you breaking down the seeds first helps make those nutrients available more quickly. They still have to break down naturally, but you would have helped start the process.

To answer your question. The oil will not negatively affect the nutritional value of the seed by not removing it. Even if it is first pressed, much of the oil will still be in the meal.

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